In addition I also had the OLED display plugged in and a script running "watch" with an interval of 5 seconds doing:
wget of a 127byte file to /tmp
oled-exp cursor 0,0 write "cat /tmp/downloadedfile.txt"

The OLED Expansion was set to default / full brightness.
I unplugged the Omega and power dock at 20 minutes past midnight.
The last log I have from the SSH session is 08:19:35

So adding the OLED Expansion and using it every 5 seconds (along with a small file get over wifi) reduces the runtime from around 11 hours to almost exactly 8 hours!

My next test will be to reduce the brightnesson the OLED display and see if and what runtime difference that makes.

For those that might be interested.. I fully charged and then tested my Power Dock / Battery Dock with the stock battery.

I had an Omega with a 1-wire temperate sensor attached and connected to my (fairly good reception) wifi. An SSH session to the Omega and a constant ping test to the Omega. It was reading the temperature from the 1-wire sensor every 2 minutes.

I unplugged the Omega from the USB power at around 6pm and left it overnight.
The SSH log seems to show that the Omega finally died (battery depleted) at around 5:20am. (11 hours 20 minutes battery life.)

Impressive runtime! And within the range expected on the wiki page. I wonder how other expansions like the relay, ethernet, gps, oled display etc.. affect the runtime.